Disc brake vacuum question

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tekslk

tekslk

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I have kinda low vacume do the disc take as much vacume to work as the drum?
 
Does it take alot of vacume to make disc brakes work? Compared to drum?
 
Would someone pm me my answer Do the disc take as much vacume as the drum to operate? Thanks
 
Can't find a spec in an old manual for required vacuum level. If you are having problems, with your low vacuum, you could set up a test of vacuum versus force out to sss if your vacuum is adequate. But it might be a bit of work; you have to measure force out versus force in.
 
a power brake booster needs 16hg to operate correctly. put a gauge on it and see what your engine is pulling. they should still work halfway decent a tad under around 12-13.
 
Ok the power drums work great untill im in town or parking, using a lot of pedal. Kinda border line, im thinking of putting disc on should i stay with the power or go to manual?
 
I'm going manual for that very reason, I pull around 13Hg and it just isn't quite enough.
 
I have a comp cam pump I was gonna retire, So should I use it keep power and go to disc or just use the power drum brakes.
 
tekslk said:
I have a comp cam pump I was gonna retire, So should I use it keep power and go to disc or just use the power drum brakes.
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its all up to you, what you want to do, and what you are using the car for. for me the pump was an instant fix, i just mount and run the pump (lol) instead of changing all the associated brake parts.
 
It takes no more vacuum to operate a booster with disc or drum. The difference is in the brakes, not the vacuum booster. You keep asking the same question over and over again, yet have given nothing to go on. So let me ask you one. What is your manifold vacuum reading at idle? Before anything can be answered, that must be answered first. Your problem could be anywhere from a low vacuum reading due to the camshaft, or a vacuum leak, to a bad booster check valve or bad booster itself. Since we are all at a disadvantage and cannot stand there and diagnose your car, how bout a little help from your end?
 
tekslk said:
I have a comp cam pump I was gonna retire, So should I use it keep power and go to disc or just use the power drum brakes.
Click to expand...
How hard do you drive the car? I see you are up in the valleys and mountains up there in Central PA....in that case, the disc brakes would be a significant advantage to you. They can take more heating on hilly/mountain roads and still brake well; drums will heat faster and lose stopping power under hard use. If it was me, it's a no brainer in that territory to switch to the manual discs, and ditch the vacuum issues.

BTW, I see no problem with the vacuum pump idea....but the harder-than-average brake use where you live is the deciding factor to me to change to the discs. Or do it all: discs and power and the pump!
 
Idle vacume in neutral about 13 in gear about 8 I have the comp pump didnt no if disc take less vacume to operate or not, I would like to get away from the pump if possible. I use car for shows cruises and drive it as often as possible all year, roads permitting. Also yes in the hills and valleys. I guess I could try manual disc first than add booster if needed.
 
1968FormulaS340 said:
Power brakes on an a body are completely unneeded.
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I have manual disks on my Duster and power disks on my Challenger. The manual disks are by far better, and I will be switching my Challenger to a manual master when I get the chance. The pedal feel is better, the effort isn't that much more, and it makes more room in the engine compartment to get at the spark plugs etc.

I ran the Duster with both manual 11 3/4" disks and now with Dr. Diffs 13" Cobra brake kit, also manual but with the later master cylinder Dr. Diff sells. Even when I had the 11 3/4" disks (same as the Challenger) on the Duster, I much preferred the manuals on the Duster to the power disks on the Challenger. And since my Duster is a '74 and the Challenger is a '72, the weight difference really wasn't all that much, only a few hundred pounds at the most. Certainly not enough to account for how much better the manual 11 3/4" disks on the Duster felt compared to the same brakes, just power, on the Challenger.
 
One more stupid question. What size would the studs for the wheel be on 10 inch drums?
 
10 drums small bolt pattern studs are 7/16"
large bolt pattern studs are 1/2"
 
So if I buy the kit with 1/2 inch studs, do I just buy new lug nuts or is there more to it? Looks like I answered my own question there uni lug so I guess i order 1/2 in lug nuts for my crager ss wheels.
 
Since you have so little vacuum, either add an electric vacuum pump (later VW's & Volvos, $50 ebay used) or switch to a manual MC - 15/16"D or 7/8"D bore. The later would be cheaper, much less clutter, and most find it works fine. I like a newer 2-bolt alum MC w/ a 2-4 bolt adapter plate ($25 ebay).
 
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